Short wave apparatus



I Dec. 3,- 1940.

F. HERRIGER SHORT WAVE APPARATUS Filed Sept. 2, 1938 INVENTOR. BY FELIX hfR/GER ATTORNEY.

Patented Dec. 3, 1940 2,223,851 I snonrgwsvn APPARATUS Felix Herriger; Berlin, Germany, assignorto'Tele funken Gesellschaft fiir Drahtlose. Telegraphic m. b. H., Berlin,. Germany,-a corporation of Ger-- many 1 Application September 2, 1938, Serial No. 228,089 In Qerrnany September 2,1937

zClaims. (01250-5151) This invention is concerned with means adapt ed to the generation or the amplification ofoscillations, especially oscillations ofultra high" frequencies. I

It is a well known fact that serious difficulties arise in the operation of master driven' ultra short wave generators or oscillatorsingeneral, espe-,

cially where the generation'of wavelengths is concerned which are of the decirnet'er or c.enti

10 meter range. On' the other hand,fhowever,- extremely great frequency stabilityfis obtainable with this kind of control. Ithas beensuggested in. the art to use. cathode ray" tubesfor' the generation of oscillations and to produce the radio frequency current byperiodicallydirecting the focussed or beamed discharge current to two or more-anodes known as collectororgathering electrodes. A discharge tube of this type con-f tains the following elements: 'A cathode which is the source of the electrons, mean's des'ig'ned'to insureconcentration or focussing of the electron pencil or beam, say,.a stop or diaphragm,'electrostatic deflector plates for the control of the cathode ray pencil passedbetween them, and two 35 gathering electrodes maintained atga positive potential. The controlpotential applied to'the said deflector plates, while the output" circuit tuned to a frequency twice thefcontrol frequency A is united with the two gathering electrodes,.f, It is also known in the art to retard thefpencil "or jet of electrons before it is passed through be tween the control plates with a'view to enhancing its deflectibility or' deflection sensitivity. How- -ever, such schemes are unserviceable for drive or'control action with ultra high frequencies. One reason for the failure of the arrangement in this regard resides in the finite rate of propagation speed of the electron pencil; another reason lies in the extension of the plate-shaped elec- 40 trodes used for deflection. In fact, it has already been recognized and admitted that Braun tubes of the conventional type are for these reasons unsuited for oscillographing ultra-short waves. It has been attempted to overcome the foregoing 45 difficulty by subdividing the deflector electrodes into several pairs of plates. This remedy, however, is imperfect because a tube of such a design will operate under optimum conditions only for very definite frequencies and working'potentials. 50 A cathode ray tube is rendered controllable by ultra high frequencies, according to the present invention, by the use of short deflector fields. The term short deflector field refers to that time which the electron requires to pass through 55 the control field which is small compared with pended drawing.

the duration of a period of the working' fr'equency; 'in' other words, only one-tenth of the period. In order to insure high deflection sen sitivity, the electrons are" subjected to a retarding action in the immediate "neighborhood of the control zone. I i v r The basic idea of'the invention shall now be described'in more detail by reference to the ap l denotesthe evacuated discharge vessel. At one end thereof there is mount'-' ed an optionally indirectly heated cathode 2 within a focussing"electrode]; .(Wehnelt cylinderor shield); The electron pencil. 4 isaccelerated by a gun or' anode. 5" in "the form of a stop 01" diaphragm and maintained at a "positive potential, l5 and by'one or more elerztrica1 lenses 6, Bffvvhich consist of two cylinders kept at constant potentials, the potential of 6 being higher than that of the diaphragm 5, while the potential of '6', in H turn, lies-above" the potential of 6 'or'else by simi larly acting magnetic lensesthe pencil is again focussed so that it will "finallyimpact upon .the retarding electrode 1 which;v for instance,r.i sof spherical or conical shape and which is .main-.

'tai'nedat, a potential being-negative relative"to" the cathode. The result is that the electrons come to a stop a short distance anteriorly of the retarding electrode so .that.- they may thenbe acted upon in an-efiective manner; even with extremely 10w control potentials. For control are used .t'wo auxiliary electrodes 8 and B which are. impressed with ultra high frequency alternating I potential and optionally also with a negative biasing voltage. In shaping this auxiliaryor accessory electrode, care must be taken so that a'-35 short fleld will be setup; in other words, that a flel-d of appreciable intensity will be present and act only on a short distance of the cathoderay pencil path. The said auxiliary electrodes consist, for instance, of two wires (placed 'perpen 4,0

sharpened. According to the polarity at a given instant of the auxiliary electrodese 8, 8, the elec tron pencil will be deflected to one of the two arms 9, 9 of the discharge vessel I, thus striking the gathering or impactor electrodes l0, l0 mou'nted therein. The latter are impressed with a high positive potential and they are united with theoutput circuit which comprises a condenser I l and a coil I 2, for instance, and which is tuned to a frequency twice the control frequency. The ultra high frequency is fed to a dipole antenna I 4, 14 through the intermediary of a coupling coil l3. It will be understood that the inductances l2, 13 are chosen low in view of the shortness of the waves; in fact, under certain circumstances they may consist of simple wire loops. Between the auxiliary electrodes 8 and 8' and the gathering electrodes l and I0, respectively, additional accelerator electrodes or guns, screen grids, etc., may be mounted if required; also electronic multiplier stages may be there interposed.

The tube of the present invention ofiers the advantage over prior types of discharge arrangements conceived for the same purpose that the cathode ray pencil is actually able to follow and respond to the ultra high frequency control potential. And this situation holds true not merely for a single wavelength but, in fact, it is independent of the working frequency. This result is obtained because of the use of a short control field and of the accumulation or baflling of the electrons inside the control zone. The use of narrow control electrodes presenting a dimension which is small in the sense of the pencil, moreover ofiers the advantage that the capacity between these electrodes is low so that it is an easy matter to maintain a high control potential. The consequence is that the use of a comparatively high control potential will offset and compensate for the short time of action upon the pencil. If the control electrodes are of appreciable length in the direction of the penciland this has invariably been true of the conventional types of tubethe transit time required by the electrons for passing the interelectrode gap is comparable with the period of the ultra high frequency. Imagining a short piece to be cut out of the electronic pencil and tracing the same en route through the control space, it will be found that the control effects during the stay inside the control space cancel out. However, this is not 0 liable or possible to occur in this invention be- 50 electrodes, with the result that it will describe the shell of a cone and will sequentiallyimpinge upon the difierent gathering electrodes. In this manner, multiphase currents are producible, and high frequency multiplications are feasible.

What is claimed is:

1. A cathode ray tube comprising an envelope containing a source of electrons at one end thereof, a pair of spaced electron collecting electrodes at the other end of said envelope for receiving said electrons, a plurality of accelerating electrodes located between said source and said collecting electrodes, and electron deflecting electrodes located on opposite sides of the path of travel of the electron stream and between said accelerating electrodes and said collecting electrodes and adapted to have an alternating current potential applied thereto, and a decelerating electrode positioned adjacent said deflecting electrodes but on the opposite side thereof from said accelerating electrodes, said deflecting electrodes comprising thin conductors transverse to the beam and adjacent to the path of travel of the electrons whereby the efiective surface of said de fleeting electrodes transverse to the beam is substantially negligible compared to the distance between said source of electrons and said decelerating electrode, the time required for electrons to pass through the field set up by said deflecting electrodes being of short duration compared to a period of time of one cycle of alternation of said applied alternating voltage.

2. A cathode ray tube comprising an envelope containing a source of electrons at one end thereof, a pair of spaced electron collecting electrodes at the other end of said envelope for receiving said electrons, an accelerating electrode and electron deflecting electrodes in the order named positioned between said source of electrons and said collecting electrodes, a decelerating electrode positioned adjacent said deflecting electrodes but on the opposite side thereof from said accelerating electrode, said deflecting electrodes being located on opposite sidesof the path of travel of the electron stream and adapted to have an alternating voltage applied thereto, said deflecting electrodes comprising strips of sheet metal positioned transversely and perpendicularly to the path of travel of the electrons whereby the time required for an electron to pass through the field set up by said deflecting electrodes is short compared to the period of time of one cycle of alternation of the applied voltage to the deflecting electrodes.

FELIX HERRIGER. 

